Efficient photo-assisted degradation of wastewater dyes using CdS nanoparticles confined in porous G-C3N4/SiO2 composites

Abstract

Porous g-C3N4/SiO2 (CNS) nanocomposite was prepared using nanosized colloidal SiO2 by a sol/gel/condensation technique from thiourea and tetraethyl-orthosilicate (TEOS). The fabricated sample was confined with different amounts of CdS nanoparticles (NPs) through precipitation route. various characterization techniques were used to determine the structural, morphological, optical, and textural properties of the investigated photocatalysts. The band gap energies and the potential positions of the valence band (VB) and conduction band (CB) levels in the nanocomposite were determined. We have also explored the different degradation behaviors of the studied photocatalysts toward Rhodamine B (Rh.B) and Remazol Brilliant blue R (Re.B) under solar light irradiation. Amongst all the utilized photocatalysts, 8CNS demonstrated the best photocatalytic performance with degradation rate constants of 0.069 min−1 and 0.022 min−1 for Rh.B and Re.B, respectively. These values are found to be higher than the corresponding rates obtained at g-C3N4 and CdS. The higher degradation efficiency and photostability of CdS/CNS nanocomposites can be attributed to the presence of SiO2 and the synergetic effect of CdS which led to improving both their surface area and charge separation efficiency. Our investigated photocatalyst were found to retain their degradation efficiency after multiple usages demonstrating their sustainability. Based on the potential positions of the reactive species and trapping studies, the photocatalytic degradation mechanism has thus been proposed using superoxide radicals (.O2–) and photoinduced holes (h+) as the main reactive species participate in the degradation process. Our findings should pave novel routes for the elimination of the environmentally toxic dyes using affordable photocatalysts.